Cosmic Distances - Chrysten Pando

Cosmic Distances DISTANCE MODULUS @ For this lab, we will focus on two techniques that can be used to measure the distance modulus of objects in deep space - supernovas and Cepheid variable stars. Before we begin, though, we must understand what “distance modulus” means. @® Read through the background material on distance modulus. @ Use the distance modulus page to complete the following table. @ Are you having trouble with this table? Watch this teacher video for help. Object Apparent Absolute Distance Distance Magnitude Magnitude Modulus (pc) (m) (M) (m - M) Star A 2.4 2.4 0 10 Star B 6 5 1 16 Star C 10 8 2 25 Star D 8.5 0.5 8 400 @ Could one of the stars listed in the table above be an RR Lyrae star? Explain why or why not. All stars in the constellation RR Lyrae have an absolute magnitude of 0.5, Star D has the appropriate absolute magnitude CEPHEIDS Next, read through the background information on Cepheid Variable Stars. Suppose that a Type Il Cepheid has an apparent magnitude (m) of 12 and a pulsation period of 3 days. Use the chart at right along with the period to find the absolute magnitude (M). Calculate the distance modulus (m - M) and then use the table on the distance modulus page to determine the Absolute magnitude distance to the Cepheid variable star. What is the distance? 6310 pc 0.3 ] 3 10 30 100 Period (days)